1. Field of the Invention
The present invention relates in general to interconnections for connecting interactive components of electronic devices. More particularly, the present invention relates to apparatus and methods for optically interconnecting printed circuit boards by connecting optical fibers having one end embedded in the printed circuit boards.
2. Description of Related Art
Optical fibers are finding increased utility within the electronics and communications industry as a means for transferring data. Additionally, optical fibers are used extensively for directly sensing temperature and pressure in a wide range of applications. In this capacity, the ability of optical fibers to attenuate transmitted radiation in response to changes in temperature and pressure is exploited to fabricate temperature and pressure sensors. The optical fiber sensors are suitable for use in virtually any application in which temperature and pressure sensors are utilized. Such applications range from analytical instrumentation requiring temperature and pressure control to automotive and aerospace use.
One emerging aerospace use for optical fiber sensors is in the field of "smart skins". In this application, optical fiber sensors are placed in an array along aircraft wing skins to sense pressure variations at specific wing locations. Based upon the pressure sensed at these locations, feedback mechanisms which are electronically connected to the optical fiber sensors control aircraft wing configuration parameters. This application and other similar uses of optical fibers frequently require large numbers of printed circuit boards which are functionally interactive. Moreover, individual optical fibers typically have one end embedded in one of the printed circuit boards and the opposite end is connected to another optical fiber which in turn has one end embedded in a printed circuit board. It is not unusual for a single system to have an extremely large number of optical interconnections between optical fibers.
It is crucial that the optical interconnections between the optical fibers do not contribute to signal loss. It is also crucial that the connected optical fibers are well aligned. This is particularly true for pressure sensors in which very small microbending attenuation changes are being detected over the total range of expected pressure changes. Optical interconnectors which are currently used in the industry generally provide low loss connections. However, many of these interconnectors require a large amount of space. One such connector is the standard snap-in type. These are configured much like a mechanical pencil and require bulky packaging to effectively fabricate an interconnection which is integral with the optical fiber system and which is also easy to connect and disconnect.
Another type of optical interconnector consists of grooves which are etched in a silicon wafer with the optical fibers held in place in the grooves with epoxy adhesive. This configuration can also require a large amount of space and the fibers are not well secured, which can cause a loss in the integrity of the interconnection. A third type of currently utilized optical interconnection is prepared by simply butting the ends of two or more glass fibers and melting the ends together to form a permanent connection. Fibers which are connected using this technique are not easily disconnected and then reconnected. Additionally, these interconnections provide no means for protecting the optical fibers at the connecting location.
It would be desirable therefore to provide a means for optically connecting printed circuit boards having embedded optical fibers, wherein the resulting optical interconnection has low loss and lies flat without bulky packaging which requires a large amount of space. It would also be desirable to provide a means for optically connecting printed circuit boards having embedded optical fibers, wherein the resulting optical interconnection can be easily disconnected and reconnected and the optical fibers are sufficiently supported to provide a reliable interconnection.